Communicating an operational state of a transport service

ABSTRACT

This document describes tools that communicate an operational state of a transport service. The transport service provides connectivity between two or more networks, enabling the networks to exchange packets. The tools detect an operational state of a transport service. After doing so, the tools may convey the operational state of the transport service to at least one of the networks through a user-to-network interface port of a network interface device, send a message to a network interface device requesting that the network interface device convey the operational state to a network connected to the network interface device, or configure a network interface device to communicate the operational state.

BACKGROUND

Service providers commonly offer transport services that enable packetcommunication between a plurality of geographically dispersed privatenetworks associated with an enterprise. Such transport services enablethe private networks to communicate with each other as if the privatenetworks were part of a single local area network. One reason theenterprise may choose to employ a transport service is that the privatenetworks may be far enough apart that it would be prohibitive for theenterprise to build its own network infrastructure connecting theprivate networks.

Although transport services are beneficial to an enterprise,conventional transport services introduce complexity that may complicatenetwork troubleshooting since conventional transport services do notnotify an enterprise subscribing to a transport service when thetransport service is non-operational.

For example, an enterprise network technician may know there is aconnectivity problem between two enterprise locations, but may not knowthat a transport service on which his enterprise relies to connect thetwo locations is non-operational. Consequently, he may unnecessarilytroubleshoot the private enterprise networks at each location that areconnected by the transport service, assuming that the problem is in theprivate enterprise networks and not in the transport service.

Unbeknownst to the network technician, such troubleshooting is futile ifthe problem lies in the transport service. Furthermore, since theenterprise network technician generally does not have access to thedevices providing the transport service, he is unable to restore thetransport service even if he knows that the problem is in the transportservice. Thus, the network technician is dependent on a service providerproviding the transport service to resolve the connectivity problem.

If the service provider is able to inform the network technician thatthe transport service is not operational, troubleshooting may be greatlysimplified. In such a scenario, the network technician could wait untilthe service provider restores the transport service before performingany network troubleshooting. In most scenarios, once the transportservice is restored, the connectivity problem is resolved withouttroubleshooting or intervention by the network technician.

SUMMARY

This document describes tools that communicate an operational state of atransport service. The transport service provides connectivity betweentwo or more networks, enabling the networks to exchange packets. Thetools detect an operational state of a transport service. After doingso, the tools may convey the operational state of the transport serviceto at least one of the networks through a user-to-network interface portof a network interface device, send a message to a network interfacedevice requesting that the network interface device convey theoperational state to a network connected to the network interfacedevice, or configure a network interface device to communicate theoperational state.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key or essentialfeatures of the claimed subject matter, nor is it intended to be used asan aid in determining the scope of the claimed subject matter. The term“tools,” for instance, may refer to system(s), method(s),computer-readable instructions, and/or technique(s) as permitted by thecontext above and throughout the document.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary operating environment in which variousembodiments of the tools may operate.

FIG. 2 is an exemplary system illustrating network interface devicescapable of communicating an operational state of a transport service.

FIG. 3 is an exemplary system illustrating a network management systemcapable of communicating an operational state of a transport service.

FIG. 4 illustrates an exemplary network interface device capable ofcommunicating an operational state of a transport service.

FIG. 5 is an exemplary system illustrating a transport service havingthree endpoints.

FIG. 6 is an exemplary process illustrating various embodiments andmanners in which the tools convey an operational state of a transportservice to a local network.

FIG. 7 is an exemplary process illustrating various embodiments andmanners in which the tools send a message to a network interface devicerequesting that the network interface device convey an operational stateof a transport service.

FIG. 8 is an exemplary process illustrating various embodiments andmanners in which the tools configure a network interface device tocommunicate the fact that a transport service is not providingconnectivity.

The same numbers are used throughout the disclosure and figures toreference like components and features.

DETAILED DESCRIPTION

Overview

The following document describes tools capable of communicating anoperational state of a transport service. An environment in which thetools may enable these and other actions is set forth below in a sectionentitled Exemplary Operating Environment. This is followed by anothersection describing exemplary ways in which the tools may act to informprivate networks relying on a transport service of the state of thetransport service. This second section is entitled Exemplary Embodimentsfor Communicating an Operational State of a Transport Service. A finalsection describes these and other embodiments and manners in which thetools may act and is entitled Other Embodiments of the Tools. Thisoverview, including these section titles and summaries, is provided forthe reader's convenience and is not intended to limit the scope of theclaims or the entitled sections.

Exemplary Operating Environment

Before describing the tools in detail, the following discussion of anexemplary operating environment is provided to assist the reader inunderstanding some ways in which various inventive aspects of the toolsmay be employed. The environment described below constitutes an exampleand is not intended to limit application of the tools to any oneparticular operating environment. Other environments may be used withoutdeparting from the spirit and scope of the claimed subject matter.

A common service provider business model involves deploying networkinfrastructure capable of connecting networks not owned by the serviceprovider, such as enterprise networks operated by business enterprises.The service provider's network infrastructure forms a shared transportnetwork that the service provider may use to provide transport servicesto a variety of subscribers.

Each transport service provides connectivity between two or more devicesconnected to the transport network that are associated with thetransport service. In addition, the transport service preventsconnectivity via a particular transport service between devices notassociated with the transport service and devices associated with thetransport service.

FIG. 1 illustrates an operating environment generally at 100 thataccommodates a plurality of transport services. The environment includestwo private networks associated with enterprise “A” 102, 104; twoprivate networks associated with enterprise “B” 106, 108; and atransport network 110 comprising a switch 112 and three networkinterface devices (NIDs) 114, 116, 118.

NID 114 comprises two user-to-network interface (UNI) ports 120, 122 anda network-to-network interface (NNI) port 124 and is connected to theswitch 112 by a physical network link 126. Similarly, NID 116 comprisesa UNI port 128 and a NNI port 130 and is connected to the switch by aphysical network link 132. Finally, NID 118 comprises a UNI port 134 anda NNI port 136 and is connected to the switch by a physical network link138.

The transport network 110 provides two transport services 142, 144. Eachtransport service allows a private network associated with the transportservice to communicate with other private networks associated with thetransport service.

For example, transport service 142 provides connectivity between privatenetworks 102 and 104, each of which is associated with enterprise “A.”NID 114, physical network link 126, switch 112, physical network link132, and NID 116 each play a part in implementing transport service 142.Enterprise “A” may use this transport service to relay general businesscommunication, such as email, between its two private networks.

Private networks 106 and 108 are not associated with transport service142 and therefore may not communicate with private networks 102 or 104via transport service 142. This is a desirable characteristic oftransport service 142 since private networks 106 and 108 belong toenterprise “B” rather than enterprise “A.”

Similarly, transport service 144 provides connectivity between privatenetworks 106 and 108, each of which are associated with enterprise “B”and prevents private networks 102 or 104 from communicating with privatenetworks 106 or 108 via transport service 144. NID 114, physical networklink 126, switch 112, physical network link 138, and NID 118 each play apart in implementing transport service 144.

Each transport service may be implemented in a number of ways. Forexample, the transport service may comprise a Virtual Local Area Network(VLAN), a Multiprotocol Label Switching (MPLS) tunnel, an MPLSlabel-switched path, or a provider-backbone-bridging tunnel.

Typically, the NID is located near the private network so that it isviewable by network technicians who maintain the private network. EachNID connects to at least one private network via a UNI port, whichserves as an interface to the transport network. A physical network linkconnects the UNI port to a device (e.g., node 103) in the privatenetwork, such as a switch or router that is operated by the enterprise.

The NID's NNI port connects the NID to other devices in the transportnetwork. In the depicted embodiment, each NNI port connects a NID to asingle switch. In other embodiments, however, the transport network maycomprise a plurality of switches, routers, or other devices capable offorwarding data packets.

Although the NIDs of FIG. 1 are depicted with a single NNI port and twoor fewer UNI ports, in general each NID may have more than one UNI portand more than one NNI port. Furthermore, although the UNI ports of FIG.1 are each associated with a single transport service, UNI portsgenerally may be associated with one or more transport services.

Each NID assigns packets it receives on a UNI port from a privatenetwork to a transport service associated with the UNI port and thenforwards the packets through the NNI port to one of the switches of thetransport network. If the NID has a plurality of UNI ports, eachassociated with a different transport service, the NNI port may forwardpackets belonging to more than one transport service. For example, NNIport 124 of NID 114 forwards packets associated with transport service142 and packets associated with transport service 144.

Consequently, a single physical network link may relay packetsassociated with a plurality of transport services. For example, packetsassociated with transport service 142 and packets associated withtransport service 144 are multiplexed onto physical network link 126.

When a NNI port receives packets from another transport network device,such as switch 112, it de-multiplexes the packets and forwards eachpacket to a UNI port associated with the transport service to which thepacket belongs. For example, NNI port 124 forwards packets it receivesthat belong to transport service 142 to UNI port 120.

If a transport service becomes non-operational, for example because oneof the physical network links relaying the transport service isphysically severed, connectivity between the private networks that thetransport service accommodates may be lost. For example, if physicalnetwork link 126 is severed, transport services 142 and 144 will nolonger be operational.

A communication application functions within the operating environmentof FIG. 1. The communication application may be configured to detect theoperational states of the transport services facilitated by thetransport network and then communicate the operational states. Forexample, the communication application may operate within a NID anddetect that a transport service associated with one of the NIDs UNIports is operational, non-operational, or partially operational. Thecommunication application may then communicate the detected operationalstate to the private network connected to the UNI port with which thetransport service is associated. The communication application isdescribed in detail below.

Exemplary Embodiments for Communicating an Operational State of aTransport Service

In one embodiment, the communication application may be part of a NIDand may detect and communicate (or in other words reflect) theoperational state of a transport service. FIG. 2 illustrates a system200 including NIDs capable of such behavior. The system 200 includes twoprivate networks 202, 204 and a transport network 206 comprising aswitch 208 and two NIDs 210, 212.

NID 210 comprises a UNI port 214 and NNI port 216 and is connected tothe switch 208 by a physical network link 218. Similarly, NID 212comprises a UNI port 220 and a NNI port 222 and is connected to theswitch by a physical network link 224.

The transport network 206 provides a transport service 226 that enablescommunication between private network 202 and private network 204. NID210, physical network link 218, switch 208, physical network link 224,and NID 212 each play a part in implementing the transport service. Thetransport service may comprise a VLAN, MPLS tunnel, MPLS label-switchedpath, provider-backbone-bridging tunnel, or other logical constructcapable of segregating packets well known to those of skill in the art.In one embodiment, private networks 202 and 204 are not connected toeach other except via the transport service 226. In another embodiment,private networks 202 and 204 may be connected via a backup communicationlink in addition to the transport service.

Each NID may comprise one or more processor(s) 232 and computer-readablemedia 234. The computer-readable media includes a communicationapplication 236 comprising a set of executable instructions that whenexecuted communicate an operational state of a transport service. Theprocessor(s) are capable of accessing and/or executing thecomputer-readable media, including the communication application.Alternatively, the communication application may be implemented in anApplication Specific Integrated Circuit, a Field Programmable GateArray, a network processor, or other device capable of performing thefunctions of the communication application described below.

In one embodiment, the communication application 236 comprises anoperational status module 238 that detects an operational state of atransport service and a conveying module 240 that conveys theoperational state of the transport service.

The operational state of a transport service may change over time. Thetransport service may be performing as expected, in which case theoperational state of the transport service is normal. During someperiods, the transport service may be non-functional and unable to relaydata packets between the private networks associated with the transportservice. In this case, the operational state of the transport service isabnormal.

The operational state of the transport service may also be abnormal ifthe transport service is providing connectivity at a reduced performancelevel or in a sub-standard manner. For example, if the transport servicerelays some packets provided by the private networks between the privatenetworks, but drops a large number of packets provided by the privatenetworks, the operational state of the transport service may becharacterized as abnormal.

The operational state may be affected by hard failures, such as asevered physical network link, power failure, or equipment failure. Theoperational state may also be affected by a soft failure, such as aconfiguration error in one of the devices of the transport network. Aplanned outage, during which a transport network operator temporarilydisables a transport service to perform maintenance tasks on thetransport network may also affect the operational state of a transportservice.

In some situations, a NID connected to a private network may continue toaccept packets on a UNI port even though the transport service is notoperational. For example, if physical network link 224 of FIG. 2 issevered, UNI port 214 of NID 210 may continue to accept packets fromprivate network 202. NID 210 may forward the packets to switch 208,which may drop the packets due to the severed physical network link.Consequently, the transport service may appear normal to private network202 despite the fact that the transport service is non-operational.

The operational status module 238 may use many techniques to detect anoperational state of a transport service. In one embodiment, theoperational status module 238 relies on maintenance points 228, 230 todetect the operational state.

The maintenance points may be placed at a plurality of points on thetransport service. For example, transport service 226 of FIG. 2 utilizestwo maintenance points. Maintenance point 228 is associated with UNIport 214 and maintenance point 230 is associated with UNI port 220.Additional maintenance points may also be placed along transport service226, such as a maintenance point associated with NNI port 216 or amaintenance point associated with NNI port 222.

Each maintenance point may monitor the transport service at theparticular point of the transport service with which the maintenancepoint is associated. For example, maintenance point 228 monitors UNIport 214. If UNI port 214 becomes disabled, maintenance point 228 mayreport the disabled UNI port to the operational status module.

In some embodiments, a maintenance point may send a message to theoperational status module indicating that a port associated with thetransport service other than the port with which the maintenance pointis associated is disabled or not fully functional.

A maintenance point may also send continuity check messages at aperiodic rate to the operational status module and the other maintenancepoints associated with the transport service. In fact, the operationalstatus module itself may comprise a maintenance point. In someembodiments, these continuity check messages may be multicast to theother maintenance points. The operational status module is aware of eachof the maintenance points associated with the transport service.

The operational status module expects to receive continuity checkmessages from each of the maintenance points. If for some reason theoperational status module does not receive a predetermined number ofcontinuity check messages from one of the maintenance points, theoperational status module detects that the transport service is nolonger completely functional.

In one embodiment, the messages sent by the maintenance points complywith the Institute of Electrical and Electronics Engineers (IEEE)802.1ag standard, although other embodiments of the operational statusmodule do not require that the messages comply with this standard.

The operational status module may also detect the status of a transportservice by initiating a loop-back procedure with a particularmaintenance point. According to the loop-back procedure, the operationalstatus module sends a loop-back packet to the maintenance point and themaintenance point returns the packet back to the operational statusmodule. If the operational status module receives the loop-back packetback from the maintenance point, the operational status module maydetect that the transport service is functional. If the operationalstatus module does not receive the loop-back packet back from themaintenance point, the operational status module may detect that thetransport service is abnormal.

Other embodiments of the operational status module do not rely onmaintenance points to detect the operational state. For example, theoperational status module may use messages and techniques defined by theIEEE 802.3ah standard to detect the operational state of a transportservice. The operational status module may also use other techniqueswell known to those of skill in the art to determine whether a transportservice is operational, partially operational, or non-operational.

In addition to the operational status module, the communicationapplication also comprises a conveying module 240. Once the operationalstatus module has detected the operational state of a transport service,the conveying module conveys the operational state. The conveying modulemay convey the operational state to a variety of entities and may conveythe operational state in a variety of ways.

In one embodiment, the conveying module conveys the operational state tothe private networks associated with the transport service. In thisembodiment, a conveying module resides on each NID and conveys the stateof a transport service to each private network connected to the NID thatis associated with the transport service. The conveying module may, inone embodiment, convey the operational state to a private networkthrough the UNI port to which the private network is connected.

If the transport service is non-operational, the conveying module maydisable the UNI ports associated with the transport service. If theoperational status module later detects that the transport service isoperational, the conveying module may enable the UNI ports associatedwith the transport service.

When a UNI port is enabled or disabled, the private network connected tothe UNI port is affected. Since the UNI port is connected to aparticular port of a particular device within the private network, ifthe UNI port is disabled, the particular port in the private network mayreport that there is no link detected on the port and may subsequentlyreport the lack of link to a network management system. A networktechnician associated with the private network that is monitoring thenetwork management system may thereby become aware that the UNI port ofthe NID is down.

Consequently, the network technician may infer that the transportservice is no longer providing connectivity between the privatenetworks. Knowing that the UNI port is down and that the transportservice is therefore non-operational is helpful since the networktechnician now knows that the connectivity problem lies with thetransport network, not with either of the private networks. Accordingly,the technician may wait for the transport network provider to fix thetransport service rather than spending time troubleshooting either ofthe private networks, which the technician may have done if he did notknow that the problem was with the transport service.

The conveying module may disable the UNI port without disabling amaintenance point associated with the UNI port so that the maintenancepoint continues to function. In fact, the maintenance point may beinstrumental in providing information the operational status modulesubsequently uses to determine that the transport service has becomeoperational.

In another embodiment, the conveying module sends a message to theprivate network conveying the operational state of the transportservice. In this embodiment, the conveying module sends the messagethrough the UNI port to the private network.

The message may comprise a packet containing information about theoperational state. For example, the message may indicate that thetransport service is operational, partially operational, ornon-operational. The message may also indicate the reason for theoperational state. For example, the message may indicate that thetransport service is non-operational due to a planned outage.

The message may comprise an IEEE 802.1ag packet, an IEEE 802.3ah packet,an IEEE 802.1AB link-layer discovery protocol packet, or other packetcapable of relaying the operational state. The message may be addressedto a network management system associated with the private network ormay be addressed broadly using, for example, a broadcast address.

The network management system may be configured to receive and identifythe message. Once the message has been received, the management systemmay notify a network technician of the operational state of thetransport service via an alarm, an email message, a page, a display, orother communication method.

In one embodiment, the conveying module conveys the operational statedirectly to a network technician by physically altering the appearanceof the NID. For example, the conveying module may display a message onliquid crystal display on the face of the NID containing the operationalstate of the transport service. The conveying module may also convey theoperational state of a transport service associated with a UNI port bychanging the color or state of one or more Light Emitting Diodes (LEDs)associated with the UNI port.

The conveying module may, in some embodiments, use more than one of themethods described above to convey the operational state of the transportservice. The conveying module may be configured with a list of possibleoperational states for the transport service along with a list ofactions to be taken for each operational state.

For example, if the transport service is non-operational, theconfiguration may specify that the conveying module is to disable theUNI ports associated with the transport service. However, if thetransport service is partially operational (for example, because itrelays packets but not without dropping a particular percentage of thepackets) the configuration may specify that the conveying module is tosend a message describing the operational state to the private networksassociated with the transport service.

The conveying module may also be configured with one or more rulesprescribing how the operational state is to be conveyed. For example,one rule may specify that a message describing the operational state besent to a private network, but only if the private networks are capableof receiving such a message. The rule may further specify that if theprivate network is not capable of receiving such messages, UNI portsassociated with the transport service should be disabled.

Other rules may be based on the capabilities of a NID on which theconveying module operates, the capabilities of a private networkconnected to the NID, the capabilities of maintenance points associatedwith the transport service, and other factors well known to those ofskill in the art.

The configuration may also specify that the conveying module is to senda Simple Network Management Protocol trap, set an alarm, send an instantmessage, or send an email message to either a network management systemassociated with one or more of the private networks or a networkmanagement system associated with the transport network.

Returning now to FIG. 2, an exemplary sequence of events will bedescribed that illustrates the operation of the communicationapplication. System 200 is configured such that transport service 226provides connectivity between private networks 202 and 204. NID 210comprises a first communication application and NID 222 comprises asecond communication application. Maintenance point 228 is associatedwith UNI port 214 and maintenance point 230 is associated with UNI port220.

The first communication application detects that the transport serviceis operational by receiving continuity check messages from maintenancepoint 230 at regular intervals. Similarly, the second communicationapplication receives continuity check messages from maintenance point228 at regular intervals.

Next, physical network link 224 is severed. Consequently, the firstcommunication application does not receive continuity check messagesfrom maintenance point 230. After a predetermined period, the firstcommunication application determines that the transport service is nolonger operational and therefore disables UNI port 214. Consequently, adevice in private network 202 connected to UNI port 214 loses link andreports the lost link to a network management system associated withprivate network 202.

Due to the severed link, the second communication application does notreceive continuity check messages from maintenance point 228.Accordingly, the second communication application disables UNI port 220.Consequently, a device in private network 204 connected to UNI port 220loses link and reports the lost link to a network management systemassociated with private network 204.

If the physical network link is restored, continuity check messages willbe received by both the first communication application and the secondcommunication application. As a result, the communication applicationswill enable UNI ports 214 and 220 and the transport service will berestored.

Had the communication applications not disabled the UNI ports, UNI port214 would have continued to receive packets from private network 202.These packets would not have been relayed to private network 204 due tothe severed physical network link. Consequently, a network technicianfor private network 202 would know that there was not connectivitybetween the two private networks, but would not know why. To solve theconnectivity problem, the network technician would likely troubleshootprivate network 202 and determine that packets were successfully beingsent to UNI port 214. Then, finding no problems with private network202, he would call the transport network provider and ask a technicianto troubleshoot the transport service.

By conveying the operational state of the transport service to privatenetworks 202 and 204, the communication applications simplifytroubleshooting for network technicians who maintain private networks202 and 204. Since the technicians know, due to the disabled UNI ports,that the reason for loss of connectivity between the private networks isdue to the transport service, they do not need to troubleshoot privatenetwork 202 or private network 204. Instead, they need only wait for thetransport network provider to restore the transport service.

In another embodiment, the communication application may be part of anetwork management system associated with the transport network. FIG. 3illustrates a system 300 including a network management system capableof such behavior. The system 300 is similar to system 200 in that itincludes the two private networks 202, 204, the transport network 206comprising the switch 208 and the two NIDs 210, 212 connected to theswitch by physical network links 218 and 224. The transport networkprovides a transport service 226 that provides connectivity betweenprivate network 202 and private network 204. System 300 also includes anetwork management system 302

The network management system may comprise one or more processor(s) 304and computer-readable media 306. The computer-readable media includes acommunication application 308 comprising a set of executableinstructions that when executed communicate an operational state of atransport network. The communication application is similar tocommunication application 208 described above, but implements slightlydifferent functionality, which is described below.

The processor(s) are capable of accessing and/or executing thecomputer-readable media, including the communication application.Alternatively, the communication application may be implemented in anApplication Specific Integrated Circuit, a Field Programmable GateArray, a network processor, or other device capable of performing thefunctions of the communication application described below.

In one embodiment, the communication application 308 comprises areceiving module 310 that receives a communication conveying theoperational state of the transport service and a sending 312 module thatsends a message to at least one of the NIDs requesting that the NIDconvey the operational state of the transport service to the privatenetwork connected to the NID.

The communication received by the receiving module may be a packet orother message. In one embodiment, the NIDs detect the operational stateof the transport service and send the communication conveying theoperational state of the transport service to the receiving module. TheNIDS may employ the maintenance points and methods described above inrelation to FIG. 2 to detect the operational state of the transportservice.

In another embodiment, the network management system is capable ofdetecting the operational state of the transport service and sends thecommunication conveying the operational state of the transport serviceto the receiving module. The network management system may also employthe maintenance points and methods described above to detect theoperational state of the transport service.

In yet another embodiment, the maintenance points described above areplaced at various points on the transport service and the maintenancepoints send the communication conveying the operational state of thetransport service to the receiving module. In this embodiment, themaintenance points determine, based on messages from other maintenancepoints, the operational state of the transport service.

Alternatively, the receiving module may receive continuity checkmessages and other messages directly from the maintenance points and maydetermine the state of the transport service from the messages. Thereceiving module may also receive the communication conveying theoperational state of the transport service from another source capableof detecting the operational state of the transport service.

Once the receiving module has received the communication conveying theoperational state of the transport service, the sending module sends amessage to at least one of the NIDs requesting that the NID convey theoperational state of the transport service to the private networkconnected to the NID. The nature of the message sent depends on theoperational state of the transport service.

If the operational state indicates that the transport service isnon-operational, the message may comprise a request that the NID disableits UNI ports associated with the transport service. Accordingly, theNID disables its UNI ports in a manner similar to that described abovein relation to FIG. 2.

In contrast, if the operational state indicates that the transportservice is operational, the message may comprise a request that the NIDenable its UNI ports associated with the transport service. Accordingly,the NID enables its UNI ports in a manner similar to that describedabove in relation to FIG. 2.

Alternatively, the message may request that the NID send a packetcomprising a message describing the operational state of the transportservice to the private network associated with the transport service.Accordingly, the NID sends one of the messages described above inrelation to FIG. 2 that describe the operational state of the transportservice.

The sending module may send the message via a management channel such asa management VLAN or an out-of-band management system that isindependent of the switch and the transport service. This embodiment ofthe communication application has the advantage of being centralized ina single location, the network management system, rather than beingdistributed onto each NID like the communication application describedabove in relation to FIG. 2.

As was described above, a NID may comprise more than one NNI port andmore than one UNI port. The communication application may manipulate thestate of these ports in various manners to accurately communicate theoperational state of one or more transport services.

FIG. 4 illustrates a switch 400 capable of communicating the operationalstate of one or more transport services. The switch 400 comprises fiveUNI ports 402, 404, 406, 408, 410 and two NNI ports 412, 414. UNI port402 is associated with transport service 416, UNI port 404 is associatedwith transport service 418, and UNI port 406 is associated withtransport service 420. NNI port 412 relays all three transport services416, 418, and 420 to a transport network device on a single physicalnetwork link 422.

To detect the operational states of these three transport services,maintenance points may be placed on each of the three UNI ports 402,404, and 406. In some embodiments, three additional maintenance pointsare placed on NNI port 412, one for each of the three transport servicesrelayed by NNI port 412.

If transport service 418 becomes non-operational, UNI port 404 may bedisabled in order to convey the fact that transport service 418 isnon-operational to a private network connected to UNI port 404. UNIports 402 and 406, however, remain enabled since transport services 416and 420 are still operational. NNI port 412 also remains enabled sinceit relays transport services 416 and 420. In this manner, UNI port 404conveys the state of transport service 418 without disturbing transportservices 416 and 420.

UNI ports 408 and 410 are both associated with transport service 424.Two UNI ports may be associated with the same transport service toprovide more bandwidth to a private network than if a single UNI portwas associated with the transport service. NNI port 414 relays transportservice 424 to a transport network device on a single physical networklink 426.

If transport service 424 becomes non-operational, UNI ports 408 and 410may both be disabled to convey the fact that transport service 424 isnon-operational to a private network connected to UNI ports 408 and 410.In this scenario, the fact that a single transport service 424 isnon-operational leads to the disabling of two UNI ports.

Although the transport services illustrated in FIG. 4 are each relayedby a single NNI port, transport services may be relayed by a pluralityof NNI ports. The plurality of NNI ports may provide the transportservices relayed by the NNI ports with additional bandwidth, redundancy,or other benefits.

A transport service may provide connectivity between more than twoprivate networks. FIG. 5 illustrates a system 500 having such atransport service. System 500 comprises three private networks 502, 504,506 and a transport network 508. The transport network comprises aswitch 510 and three NIDS 512, 514, 516. A single transport service 518provides connectivity between all three private networks.

In this embodiment, a communication application such as communicationapplication 236 described above in relation to FIG. 2 may reside on eachNID. Alternatively, a communication application such as communicationapplication 308 described in relation to FIG. 3 above may reside on anetwork management system (not illustrated). The communicationapplication may determine that transport service 518 is providingconnectivity to two of the private networks but that the third privatenetwork does not have connectivity.

For example, if the physical network link 520 connecting NID 516 to theswitch was severed, private network 506 would not have connectivity toprivate networks 502 and 504. Private networks 502 and 504, however,would still have connectivity with each other.

In such a situation, the communication application may be configured toconvey the state of transport service 518 by sending a messagedescribing the operational state of the transport service to privatenetworks 502 and 504 as was described above in relation to FIG. 2. Inaddition, the communication application may disable the UNI port (notillustrated) of NID 516 to which private network 506 is connected.

In this manner, connectivity between private networks 502 and 504remains in place and private networks 502 and 504 both know about thelack of connectivity to private network 506. Transport service 518appears appropriately to be non-operational to private network 506 sinceprivate network 506 does not have connectivity to either of the otherprivate networks. This situation may be preferable to disabling UNIports on NIDs 512 and 514, which would prevent connectivity betweenprivate networks 502 and 504 even though such connectivity is possible.

If, however, the operational state of transport service 518 is such thatnone of the private networks have connectivity to each other, such as ifswitch 510 experienced a power failure, the communication applicationmay disable the UNI ports (not illustrated) of NIDs 512, 514, and 516 towhich private networks 502, 504, and are connected. Such actioncommunicates the fact that no connectivity between private networks iscurrently available.

The communication application may also use other methods of conveyingthe operational state of a transport service connecting three or moreprivate networks. For example, the communication application may send amessage to the private networks indicating which of the private networksassociated with a transport service currently have connectivity andwhich do not.

Other Embodiments of the Tools

The section above describes exemplary ways in which the toolscommunicate an operational state of a transport service. The sectionbelow describes additional embodiments of the tools, includingprocesses. Each of the processes below may be performed throughcomputer-executable instructions on computer-readable media, hardware, acombination of both, or otherwise. FIG. 6 illustrates a process 600 as aseries of blocks representing individual operations or acts performed bythe tools.

At block 602, the tools detect an operational state of a transportservice. The tools may detect the operational state using one of thetechniques described above in relation to FIG. 2 or may use othertechniques capable of detecting the operational state of the transportservice.

The transport service terminates, at one end, at a user-to-networkinterface (UNI) port of a network interface device (NID). The transportservice may be one of the transport services described above in relationto FIGS. 1-5.

Alternatively, the transport service may be a network construct capableof providing connectivity between two private networks and capable ofsegregating packets associated with the transport service from packetsnot associated with the transport service. As was describe above, insome embodiments the transport service may be a VLAN, an MPLS tunnel, anMPLS label-switched path, or a provider-backbone-bridging tunnel.

The UNI port may be one of the UNI ports described above in relation toFIGS. 1-5 and is connected to a local network, such as the privatenetworks described above. The UNI port may also be a port connecting aprivate network to a transport network. The transport service utilizestwo or more physical network links to relay data packets between the UNIport and at least one remote network, such as the physical network linksdescribed above.

At block 604, the tools convey the operational state of the transportservice to the local network through the UNI port. As was describedabove in relation to FIG. 2, the tools may convey the operational stateby enabling or disabling a UNI port, sending a message to the localnetwork via the UNI port, or by displaying a message on the NID.

FIG. 7 illustrates another embodiment of the tools as method 700, whichis illustrated as a series of blocks representing individual operationsor acts performed by the tools. At block 702, the tools receive acommunication conveying the operational state of a transport servicehaving two or more endpoints. Each endpoint is associated with adifferent NID. The transport service relays data packets between two ormore distinct private networks and each of the distinct private networksis connected to a different one of the NIDs.

The communication may be received from a maintenance point, a NID, or amanagement system as was described above in relation to FIG. 3. Thecommunication may also be received from another entity as long as theentity is capable of detecting or relaying the operational state of thetransport service.

At block 704, the tools send a message to at least one of the NIDs. Themessage requests that the NID convey the operational state of thetransport service to the private network connected to the NID. As wasdiscussed above in relation to FIG. 3, the message may request that theNID enable or disable a UNI port or send a message conveying theoperational state through the UNI port. The message may also requestthat the NID enable or disable a NNI port or that the NID display theoperational state on its face or through LEDs.

FIG. 8 illustrates another embodiment of the tools as method 800, whichis illustrated as a series of blocks representing individual operationsor acts performed by the tools. At block 802, the tools determine that apacket transport service utilizing at least two physical network linksand intended to provide connectivity between a plurality of distinctprivate packet networks via the physical network links is not providingthe intended connectivity. The packet transport service utilizes a setof network interface devices, each connected to one of the privatepacket networks.

The packet transport service may be one of the transport servicesdescribed above in relation to FIGS. 1-5. Alternatively, the packettransport service may be a network construct capable of providingconnectivity between two private networks and capable of segregatingpackets associated with the transport service from packets notassociated with the transport service. As was described above, in someembodiments the transport service may be a VLAN, an MPLS tunnel, an MPLSlabel-switched path, or a provider-backbone-bridging tunnel.

At block 804, the tools configure at least one of the NIDs tocommunicate the fact that the packet transport service is not providingthe intended connectivity. As was discussed above in relation to FIG. 2,the tools may configure the NID to enable or disable a UNI port, displaya status message on the NID, enable a status LED of the NID, or send amessage describing the lack of connectivity between the private packetnetworks. The tools may also configure the NID to send an email message,Simple Network Management Protocol trap, or other communication.

CONCLUSION

The above-described tools communicate an operational state of atransport service. By so doing, the tools simplify the process ofnetwork troubleshooting. Although the tools have been described inlanguage specific to structural features and/or methodological acts, itis to be understood that the tools defined in the appended claims arenot necessarily limited to the specific features or acts described.Rather, the specific features and acts are disclosed as exemplary formsof implementing the tools.

1. A method comprising: receiving, with a user-to-network interface(UNI) port of a network interface device, first packets from a node of alocal network, the node being physically distinct from the networkinterface device; modifying, using the network interface device, thereceived first packets to be compatible with a transport servicecomprising two or more physical links and having at least two endpoints,one of the endpoints being located on the network interface device andwherein the node of the local network is not part of the transportservice; forwarding, utilizing the transport service and the networkinterface device, the modified first packets to a remote networkassociated with another one of the endpoints via a network-to-networkinterface (NNI) port of the network interface device; receiving, usingthe network interface device, second packets via the transport serviceand the NNI port of the network interface device; modifying, using thenetwork interface device, the second packets so the second packets areno longer part of the transport service and then forwarding the modifiedsecond packets to the node of the local network; accessing, using thenetwork interface device, information describing an operational state ofthe transport service; and sending, using the network interface device,a packet conveying the information describing the operational state ofthe transport service to the node of the local network through the UNIport.
 2. The method of claim 1, further comprising enabling the UNI portif the operational state is normal and disabling the UNI port if theoperational state is abnormal.
 3. The method of claim 1, wherein thepacket conveying the information comprises an Institute of Electricaland Electronics Engineers (IEEE) 802.1ag packet, an IEEE 802.3ah packet,or an IEEE 802.1AB link-layer discovery protocol packet.
 4. The methodof claim 1, wherein the accessing comprises receiving an IEEE 802.1agcontinuity check message packet comprising a link status fault messagefrom a maintenance point.
 5. The method of claim 1, wherein thetransport service is the only transport service associated with the UNIport.
 6. A method comprising: detecting an operational state of atransport service, the transport service terminating, at one end, at auser-to-network interface (UNI) port of a network interface device andutilizing two or more physical network links to relay data packetsbetween the UNI port and at least one remote network, the UNI port beingconnected to a local network; sending a packet conveying the operationalstate of the transport service to a node of the local network throughthe UNI port wherein the node does not relay the data packets of thetransport service and is physically distinct from the network interfacedevice; wherein detecting the operational state of the transport servicefurther comprises detecting the operational state of the transportservice at one or more maintenance points located on the transportservice; and wherein: another end of the transport service terminates ata second UNI port of a second network interface device, the remotenetwork being connected to the second UNI port; one of the maintenancepoints is located at the UNI port and another of the maintenance pointsis located at the second UNI port; and further comprising disabling theUNI port without disabling the maintenance point located at the UNIport.
 7. A method comprising: receiving a communication conveying anoperational state of a transport service having two or more endpointseach associated with a different network interface device (NID), thetransport service relaying data packets between two or more distinctprivate networks, each distinct private network being connected to adifferent one of the NIDs; sending a message to a first port of at leastone of the NIDs requesting that the at least one NID convey theoperational state of the transport service to the private networkconnected to the NID; wherein each NID comprises a UNI port that isassociated with the transport service and is directly connected to oneof the private networks; wherein the message comprises a request todisable the UNI port of the at least one NID to which the message issent, the first port being physically distinct from the UNI port of theat least one NID; wherein one of the NIDs comprises a plurality ofuser-to-network interface (UNI) ports and at least onenetwork-to-network interface (NNI) port, at least one of the UNI portsbeing associated exclusively with the transport service and at least oneof the UNI ports being associated exclusively with a second transportservice; wherein both the transport service and the second transportservice are relayed by the NNI port; and wherein the message requeststhat the NID disable all of the UNI ports associated with the transportservice without disabling either the NNI port or the UNI port associatedwith the second transport service.
 8. The method of claim 7, whereinsending a message comprises sending a message requesting that the NIDsend a packet comprising a message describing the operational state ofthe transport service to a node of the private network connected to theNID wherein the node does not relay the data packets of the transportservice and is physically distinct from the NID.
 9. The method of claim7, wherein the communication is received from a network managementsystem, a maintenance point, or a NID.
 10. The method of claim 7,wherein the distinct private networks are not connected to each otherexcept through the transport service.
 11. A method comprising: detectingan operational state of a transport service facilitated by an NNI portof a network interface device, the transport service terminating, at oneend, at the network interface device and utilizing two or more physicalnetwork links to relay data packets between a local network and at leastone remote network, a UNI port of the network device being connected tothe local network, the UNI port being physically distinct from the NNIport; and as a result of the detecting of the operational state,conveying the operational state of the transport service by disablingthe UNI port or visually conveying the operational state via one or morevisual indicators of the network interface device; wherein detecting theoperational state of the transport service further comprises detectingthe operational state of the transport service at one or moremaintenance points located on the transport service; wherein another endof the transport service terminates at a second UNI port of a secondnetwork interface device, the remote network being connected to thesecond UNI port; wherein one of the maintenance points is located at theUNI port and another of the maintenance points is located at the secondUNI port; and wherein the disabling the UNI port is without disablingthe maintenance point located at the UNI port.
 12. The method of claim11, wherein the detecting comprises detecting a failure to receive apredetermined number of Institute of Electrical and ElectronicsEngineers (IEEE) 802.1ag continuity check messages from a maintenancepoint.
 13. The method of claim 11, wherein the conveying of theoperational state comprises visually conveying the operational state viathe one or more visual indicators by displaying a status message on theNID.
 14. The method of claim 11, wherein the transport service utilizesa plurality of devices connected by the physical network links to relaydata packets between the local network and the at least one remotenetwork.
 15. The method of claim 11 wherein the detecting comprisesreceiving an IEEE802.1ag continuity check message packet comprising alink status fault message from a maintenance point.
 16. The method ofclaim 11 wherein the detecting comprises: a first node transmitting aloopback packet intended for a second node, the second node beinglocated on the transport service; and determining that the first nodehas not received the loopback packet back from the second node.
 17. Themethod of claim 11 wherein the conveying of the operational statecomprises visually conveying the operational state via the one or morevisual indicators by illuminating at least one light emitting diode ofthe NID.